US3753418A - Coating apparatus with fluid doctor blade - Google Patents

Coating apparatus with fluid doctor blade Download PDF

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Publication number
US3753418A
US3753418A US00144186A US3753418DA US3753418A US 3753418 A US3753418 A US 3753418A US 00144186 A US00144186 A US 00144186A US 3753418D A US3753418D A US 3753418DA US 3753418 A US3753418 A US 3753418A
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United States
Prior art keywords
nozzle
fluid
metal strip
slot
lip
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Expired - Lifetime
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US00144186A
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English (en)
Inventor
R Roncan
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Nuova Italsider SpA
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Italsider SpA
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Assigned to NUOVA ITALSIDER S.P.A., A CORP. OF ITALY reassignment NUOVA ITALSIDER S.P.A., A CORP. OF ITALY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ITALSIDER S.P.A.
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
    • C23C2/16—Removing excess of molten coatings; Controlling or regulating the coating thickness using fluids under pressure, e.g. air knives
    • C23C2/18—Removing excess of molten coatings from elongated material
    • C23C2/20—Strips; Plates

Definitions

  • An object of the present invention is to provide an improved device for the adjustment of the zinc coating on a steel sheet or the like during operation of the device.
  • the strip of metal sheet coming from the zinc bath passes between two metal rollers, called galvanizing rollers.
  • galvanizing rollers By adjusting the speed, the mutual pressure and the passage of said rollers within the bath, it is possible to modify the thickness and thus the weight of said zinc coating.
  • Such a method has the advantage of galvanizing at a low speed, the thicknesses of the coating being related to the thermal capacity of the furnaces.
  • it has the following disadvantages:
  • the second method for adjusting the thickness of the zinc coating comprises two thin fluid blasts (generally consisting of steam or air) at a controlled temperature and pressure, directed on the two surfaces of the metal strip coming from the zinc bath.
  • Such fluid blasts are commonly called air or steam blades or knives.
  • the fluid blade method has the disadvantage that it cannot be used when the strip is run below a given minimum speed. Such a disadvantage however, may be overcome by increasing the capacity of the heating furnaces. On the other hand, said fluid blade method has the following advantages:
  • the better uniformity of .the zinc coating allows for a reduction in the zinc consumption up to about 10 percent;
  • Such a disadvantage consists of the difficulty of obtaining in a simple and economic manner nozzles which may be capable of generating fluid blades whose fluid/dynamic characteristics may be the most constant possible from one end to the other of the corresponding blades.
  • One of the method at present used is that of providing such nozzles for the fluid blades in the form of two substantially rectilinear and parallel lips which fed by a header collecting pressure fluid through a set of several conduits distributed along the whole length of said header.
  • inside said header are several suitably arranged baffle plates having the function of making uniform the outlet direction of the fluid from said header through said lips.
  • a first object of the present invention is to remove such disadvantages.
  • the lips of the nozzles suitable to generate said fluid blades must however be shaped such that the width of the fluid blade may be slightly narrower at the centre of the metal strip than at the two edges of said strip. It was found that such a difference in thickness of the fluid blade results iii a greater quantity of coating at the center of the galvanized strip.
  • the thickness of the fluid blade as between the center and the edges of the galvanized strip must be maintained substantially constant within restricted limits with any variation of the width of the strip to be galvanized.
  • Such a requirement was met, according to the known art, by providing the lips of the nozzles for the fluid blades with a stationary portion and a movable portion, or better a portion replaceable when desired, the latter allowing, according to the width of the strip to be galvanized, to obtain the desired thickness of the fluid blades corresponding to the strip edges.
  • the object of the present invention is to overcome the above described disadvantages and further to permit to vary as desired the thickness of the fluid blade along the whole length thereof and to thus control the thickness of said fluid blade continuously, i.e., during the operations thereof.
  • the improved device for the continuous adjustment of the zinc coating on a sheet in form of a strip coming from a bath of molten zinc at controlled temperatured of the type comprising a pair of substantially horizontal headers arranged just above the bath surface on both sides of said metal strip, said headers being provided each with a elongated slotted nozzle consisting of two lips capable of projecting a fluid blade onto the surface of said strip, is characterized in that at least one of said lips is elastically deformable so as to allow a variations in the outlet port of said nozzle even during its operation and without interfering with the fluid blade, either for the whole length thereof or from point to point thereof as predetermined; and further in that each of said headers has a sufficiently large section, as a function of the pressure of feeding of said fluid blade, and the delivery thereof, as inside said headers the fluid may be in a substantially quiet condition or subject to displacement the speed of which may be negligible with respect to the outlet speed of said fluid blade.
  • each of said headers is fed by two conduits and possibly by only one, heading to the ends or end of said header.
  • Said device is then characterized in that the diameters of said headers is between I and 300mm. when the thickness of the port of the slot-like nozzles is between 0.5 mm. and L mm. approximately, and when the feeding pressure of the fluid is between 600 and l,800 mm. approximately of H20.
  • Said device is also characterized in that said header is provided with a large longitudinal opening directed downwards and towards the metal strip, said opening extending, reducing its size to a nozzle, by means of two lips, the upper one, which is stationary has its inner face inclined downwards for about 3060, while the lower one has its inner face substantially horizontal; said upper lip having its inner face related to the bottom, so that its edge may be substantially parallel to the inner face of the lower lip.
  • Said device is characterized in that said lower lip near its fastened base is provided on its lower face with a narrower portion preferably in form of a slot, said portion being capable of allowing an elastic bending thereof under the action of pulling or pushing means arranged at selected distances under its lower face, so as to be in position to vary as desired said bending along the entire length thereof, and thus so as to be in position to vary as desired the nozzle port (and thus the thickness of the fluid blade) from point to point along its entire length.
  • Said device is further characterized in that said pulling or pushing means of said lower lip of the nozzle consist of sapced pins, projecting under the lower lip; the lower end of said pins being connected to axial positioning means singularly remote controlled by means of suitable back means.
  • Said device is then characterized in that it comprises angular positioning means for the two slot-like nozzles. Said device is still characterized in that it comprises horizontal positioning means capable of moving farther from and closer respectively to said metal strip the two slot-like nozzles.
  • Said device is also characterized in that said headers hang each by means of a pair of feeding conduits heading to the two ends of said headers; said feeding conduits being further preferably jointed each about a horizontal axis which is parallel to the corresponding slotlike nozzle.
  • Said device is still characterized in that the inner nozzle, that is the nozzle feeding the fluid blade onto the metal strip face against which is compressed a stabilizing roller immersed in the bath, is slightly upwardpositioned with respect to the other slot-like nozzle.
  • Said device is finally characterized in that said inner nozzle in its lowest position directs the corresponding fluid blade according to a plane substantially perpendicular to the metal strip; the fluid blade of the other slot-like nozzle being inclined downwards for about 10.
  • FIG. I is a side view according to a vertical plane per pendicular to the fluid blade plane, of a device accord ing to the invention.
  • FIG. 2 is a sectional view of a detail of FIG. I, that is a sectional view of thenozzle suitable to provide the fluid blade according to the invention.
  • numeral 1 is a metal strip stretched between two guide rollers not shown, drawn to the direction of arrow 2 and coming from a molten zinc bath 3 which is maintained at a suitable temperature.
  • Numeral 4 is a stabilizing roller having the object of positioning exactly the lying plane of the metal strip 1 mainly with respect to the nozzles 5 and 6 generating the fluid blades and arranged just above a surface 7 of bath 3, at a distance which should be between and 500mm.; the minimum values of such a gap are easily obtainable by the claimed nozzle, as it will appear herebelow, while it is very difficult to obtain them by means of conventional devices.
  • Said nozzles 5 and 6 are fed by back headers, 8 and 9 respectively, which mainly consists of two preferably circular conduits the diameter of which is large in comparison to the thickness of the fluid blades.
  • Said headers are fed only through two conduits 10 and I! which are pivoted about horizontal and transversal axes l2 and [3 by means of suitable sealing joints l4 and 15 which are turnable.
  • Said two joints are provided with two toothed sections 16 and 17 engaging each other, so that a rotation of the conduit portion 10 is always accompanied by a contrary and equal rotation of conduit It and viceversa.
  • conduits l0 and 11 which obviously accompanies a relative movement of nozzles 5 and 6 to or from each other and'the metal strip 1, is caused by a pair of double-action jackes 18 arranged at the two ends of headers 8 and 9 or directly connected to the outer surfaces of conduits 10 and 11 which have the function too of supporting on both sides headers 8 and 9.
  • header 8 By a dashed-line, with 8', is shown header 8 in a lateral tilted position.
  • jack 18 has further the object of allowing to vary the distance of nozzles S and 6 from said metal strip 1 and to vary accordingly the angle between the fluid blades and said metal strip 1.
  • said two fluid blades are arranged slightly staggered in height, i.e. the inner nozzle 5 is in a slightly higher position than the outer nozzle 6.
  • inner nozzle is meant the one projecting its fluid blade on the face of said metal strip 1 which is not in contact with the adjusting roller 4.
  • the outer nozzle 6 is more inclined towards the bottom for about 10. Such a difference in inclination obviously remains when both nozzles are rotated outwards for adjusting their distance from said metal strip 1.
  • said nozzle 6 comprises a cylindric header 8 which at the outer and lower part has a flattened surface 20 substantially horizontal which is suitable to provide support for brackets 21 for the means controlling the opening of said nozzle along the entire length of its.
  • header 8 In a direction inclined downwards for about 459, header 8 has a large longitudinal port 22 on the edges of which are fastened an upper lip 23 and a lower one 24, eg by means of screws 25. While the position of the upper lip 23 is stationary, said lower lip 24 may be inclined downwards elastically, as it has a longitudinal groove 26 on its fastening base and on its outer face. Said lip 24 ispassed through by suitably spaced pins 27, arranged e.g. each 10 cm., the head of which is housed is suitable bores, so as not to project from the upper face of lip 24. The lower end of pins 27 may be drawn downwards for distances selected and fifferent from pin to pin, so that the thickness of the fluid blade coming from nozzle 6 may be adjusted as desired for its entire length.
  • the thickness of the fluid blade may have the desired values. And moreover the thickness of said fluid blade, along the width of said strip 1, may be varied from a minimum value at the enter of said strip to a maximum value at the edges of same, with a linear, parabolic, circular behaviour and in any other way considered suitable.
  • the end of pin 27 is supported in a turnable and axially slidable way by bushes fastened at the end of bracket 21.
  • a portion of said pin is further threaded and on same is screwed a turnable but axially stationary wheel 30 which is provided outside with a helical toothing engaging a second wheel arranged at not shown, and rotated by a shaft 31 which is remote controlled, even during the device operation.
  • the downward displacement of pin 27 may be obtained mechanically in any other similarly suitable way.
  • the diameter of said header 8 may be large with respect to the thickness of the fluid blade. In practice, it is advisable that said diameter may be selected between and 300mm. However, the choice of said diameter must be made as a function of the feeding pressure of the fluid, the thickness of the fluid blade and mainly the delivery thereof, so that the fluid under pressure contained inside said header 8 may be practically stationary. In such a way, the fluid blade will have the same orientation along its whole length and any turbulence will be avoided near the nozzle opening as well as any different fluid/dynamic behaviour of said fluid blade along its length. In other words, the size of said header 8 must be so large as to allow same to act as a lung.
  • the upper lip 23 is to be inclined downwards for about 45 and its inner face is to be connected so as to be tangent, correspondingly to its lower end, to the inner face of the lower lip 24 whose lying position defines the lying plane of said fluid blade.
  • An improved device for the continuous adjustment of the zinc coating on a metal strip coming from a molten zinc bath at controlled temperature comprising a pair of horizontal manifolds arranged for positioning just above the bath surface on both sides of the metal strip, said manifolds each comprising an elongated nozzle, each of said manifolds being supported by a pair of pivotally mounted feed conduits which communicate with the ends of said each manifold, means to simultaneously adjust the pair of nozzles with respect to angular relationships and the distance therebetween, each said nozzle comprising a pair of elongated lip members deflning therebetween slot 'means for directing a stream of gases from saidelongsted nozzle to impinge on the sides of the metal strip wherein the lower lip, near its base, is fastened to said manifold and is provided on its lower face with a slot parallel to said elongated nozzle, characterized in that said lower lip comprises deformable means for varying the longitudinal profile of said slot means, a plurality of pulling and
  • each of said manifolds is between 100 and 300 mm, when the thickness of the port of the slotJike nozzle is between 0.5 and 1.5 mm, and when the feeding pressure of the fluid is between 600 and 1,800 mm of H,O.
  • nozzles comprise inner and outer nozzles, the inner nozzle feeding its respective fluid blade onto the metal strip face opposite that against which is compressed a stabilizing roller immersed in the bath, said inner nozzle being in a slightly upper position with respect to the other nozzle.
US00144186A 1970-05-27 1971-05-17 Coating apparatus with fluid doctor blade Expired - Lifetime US3753418A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT1271170 1970-05-27

Publications (1)

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US3753418A true US3753418A (en) 1973-08-21

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US (1) US3753418A (de)
DE (2) DE7119126U (de)
FR (1) FR2090313B1 (de)
GB (1) GB1341766A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4078103A (en) * 1975-04-17 1978-03-07 Armco Steel Corporation Method and apparatus for finishing molten metallic coatings
US4655163A (en) * 1984-07-30 1987-04-07 Hokenson Earl G Apparatus for pressing corrugated web against glue applicator roll
US5064118A (en) * 1990-12-26 1991-11-12 Bethlehem Steel Corporation Method and apparatus for controlling the thickness of a hot-dip coating
US5423913A (en) * 1991-10-30 1995-06-13 Fontaine; Paul P. Apparatus and method for control of metallic coating-weight by the use of gas knives
US6019291A (en) * 1997-05-07 2000-02-01 B. W. Vortex, Inc. Fluid knife
US6199301B1 (en) * 1997-01-22 2001-03-13 Industrial Automation Services Pty. Ltd. Coating thickness control
US7563322B2 (en) 2007-04-09 2009-07-21 West Virginia University Method and apparatus for online flow control over the span of a high aspect ratio slot jet

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1023842B (it) * 1974-08-08 1978-05-30 Italsider Spa Dispositivo perfezionato per insufflare una lama d aria contro un nastro rivestito da uno strato di materiale liquido, in particolare contro un nastro metallico rivestito da uno strato di zico fuso
FR2690170B1 (fr) * 1992-04-17 1995-03-31 Clecim Sa Dispositif à lame d'air de régulation d'un dépôt métallique.
DE69426357T2 (de) * 1994-07-14 2001-04-05 Fontaine Eng & Maschinen Gmbh Vorrichtung und Verfahren zum Kontrollieren der Beschichtungsgewicht eines metallüberzuges mittels Blasdüsen

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1980923A (en) * 1931-08-18 1934-11-13 Warren S D Co Method of and apparatus for coating paper
US2139628A (en) * 1936-05-06 1938-12-06 Warren S D Co Air doctor
US2390007A (en) * 1943-12-31 1945-11-27 Dominion Foundries & Steel Apparatus for continuously hot dip coating of tin on coiled strip
US2940418A (en) * 1959-03-27 1960-06-14 Black Clawson Co Paper machinery
US3607366A (en) * 1968-11-14 1971-09-21 Yawata Iron & Steel Co Removal of excess molten metal coatings by gas blast without ripple formations on coated surfaces

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LU55386A1 (de) * 1967-02-02 1968-04-11

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1980923A (en) * 1931-08-18 1934-11-13 Warren S D Co Method of and apparatus for coating paper
US2139628A (en) * 1936-05-06 1938-12-06 Warren S D Co Air doctor
US2390007A (en) * 1943-12-31 1945-11-27 Dominion Foundries & Steel Apparatus for continuously hot dip coating of tin on coiled strip
US2940418A (en) * 1959-03-27 1960-06-14 Black Clawson Co Paper machinery
US3607366A (en) * 1968-11-14 1971-09-21 Yawata Iron & Steel Co Removal of excess molten metal coatings by gas blast without ripple formations on coated surfaces

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4078103A (en) * 1975-04-17 1978-03-07 Armco Steel Corporation Method and apparatus for finishing molten metallic coatings
US4655163A (en) * 1984-07-30 1987-04-07 Hokenson Earl G Apparatus for pressing corrugated web against glue applicator roll
US5064118A (en) * 1990-12-26 1991-11-12 Bethlehem Steel Corporation Method and apparatus for controlling the thickness of a hot-dip coating
US5423913A (en) * 1991-10-30 1995-06-13 Fontaine; Paul P. Apparatus and method for control of metallic coating-weight by the use of gas knives
US6199301B1 (en) * 1997-01-22 2001-03-13 Industrial Automation Services Pty. Ltd. Coating thickness control
US6019291A (en) * 1997-05-07 2000-02-01 B. W. Vortex, Inc. Fluid knife
EP0876854A3 (de) * 1997-05-07 2000-08-09 B.W. Vortex, Inc. Fluidmesser
US7563322B2 (en) 2007-04-09 2009-07-21 West Virginia University Method and apparatus for online flow control over the span of a high aspect ratio slot jet

Also Published As

Publication number Publication date
DE7119126U (de) 1971-11-25
FR2090313A1 (de) 1972-01-14
FR2090313B1 (de) 1974-04-26
DE2124302A1 (de) 1972-02-10
DE2124302C3 (de) 1979-04-26
DE2124302B2 (de) 1977-04-21
GB1341766A (en) 1973-12-25

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Date Code Title Description
AS Assignment

Owner name: NUOVA ITALSIDER S.P.A., GENOA, ITALY, VIA CORSICA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ITALSIDER S.P.A.;REEL/FRAME:003995/0338

Effective date: 19820504